The present invention relates to a watch provided with a tourbillon including a regulating device engaging with an escapement which itself engages with a pinion meshing with a fixed wheel, the regulating device, the escapement and the pinion being mounted on a plate fixed to a pipe rotatably mounted in a support plate, this pipe being situated at the center of the watch and driven in rotation by a driving device.
A tourbillon watch answering the generic description given above is described in Swiss Patent No. 33 368. This document describes a watch movement whose regulating device and escapement are carried by a plate rotatably mounted at the center of the movement. The plate is fixed to a central pipe which ends in a pinion driven by a barrel spring via a wheel and pinion set formed of one wheel and one pinion, so that the plate is driven continuously in rotation with the pipe which is used as its pivoting shaft.
The pipe is engaged on a shaft which carries the minutes hand, this shaft ending in a pinion meshing with a wheel which is friction-tight fitted on a cover of the barrel. A cannon pinion is driven onto the shaft and follows the pipe. The cannon pinion drives a cannon wheel which carries the hours hand via a motion work. Moreover, the motion work is covered by a dial. It is clear from the foregoing that the plate is not entirely visible through the crystal since a motion work, which is itself hidden by a dial, is mounted above it.
It will further be noted that the escapement pinion is situated above the plate, so that the fixed wheel with which it meshes is also above the plate. This fixed wheel is secured to a bridge carried by four narrow arms, this bridge being placed on the plate. Consequently, the plate is partly hidden from view, not only by the motion work and the dial, but also by the central bridge and the arms connecting it to the movement support plate.
In conclusion, the tourbillon mechanism described in the aforecited Patent barely allows the elements of which it is constituted to be seen, in fact only the balance which rotates on itself and about the dial is visible. Conversely, the present invention proposes a rotating plate which is entirely visible from its center to its periphery, thus allowing the whole of the tourbillon mechanism to be seen.
The invention is characterized in that the fixed wheel and the pinion meshing therewith are situated below the plate. This allows the space above the dial to be freed of any fixed elements and any supports intended to carry such elements.
In a preferred embodiment, the pipe carrying the plate surrounds a cannon pinion carrying a minutes hand, this cannon pinion itself surrounding a shaft carrying an hours hand, the shaft and the cannon pinion being connected to each other by a motion work situated below the plate.
In another embodiment which does not include a cannon pinion, a minutes hand or indicator is mounted on the plate, while the pipe surrounds a shaft carrying an hours hand, the shaft and the pipe being connected to each other by a motion work situated below the plate.